Methods and apparatuses facilitating fluid flow into via holes, vents, and other openings communicating with surfaces of substrates of semiconductor device components

ABSTRACT

A method for removing material from surfaces of at least a portion of at least one recess or at least one aperture extending into a surface of a substrate includes pressurizing fluid so as to cause the fluid to flow into the at least one recess or at least one aperture. The fluid may be pressurized by generating a pressure differential across the substrate, which causes the fluid to flow into or through the at least one aperture or recess. Apparatus for pressurizing fluid so as to cause it to flow into or through recesses or apertures in a substrate are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.11/351,640, filed Feb. 10, 2006, scheduled to issue as U.S. Pat. No.8,076,244 on Dec. 13, 2011, the disclosure of which is herebyincorporated herein by this reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to techniques for exposing orapplying substrates of semiconductor device components to fluids and,more specifically, to methods in which fluid flows or is forced beyond afeature. In a particular example, the present invention relates to etchtechniques and, more specifically, to etch methods in which an etchantflows or is forced beyond a feature while etching the feature. Moreparticularly, the present invention relates to methods for forming ventholes of desired dimension in the bottom of so-called “blind ended” viaholes. The present invention also relates to apparatus for causing anetchant to flow across a feature to be etched.

2. Background of Related Art

A variety of processes have been developed to form via holes throughsubstrates, including semiconductor substrates, such as silicon wafers.Some via holes are formed so as to extend completely through asubstrate, while others, which are referred to in the art as “blindended” via holes, extend only partially through the substrate.

A blind ended via hole may be formed in the surface of a substrate by avariety of processes, including etch techniques that are timed in such away as to permit the hole to extend only partially through the thicknessof the substrate, which thickness may typically be about 700 μm to about800 μm in the case of a full-thickness semiconductor wafer.

When blind ended via holes are formed in one surface of a substrate, avent, which communicates with the via hole, may be formed in the other,opposite surface of the substrate. The presence of a vent facilitatesthe introduction of materials into and the formation of material layerswithin the relative small (typically about 50 μm diameter) via hole. Thesize of the vent hole is typically small relative to (e.g., about onetenth of) the size of the blind ended via hole (e.g., about 5 μmdiameter).

A vent may be formed by directing a laser beam of appropriate wavelengthand intensity onto the surface of the substrate opposite the mouth ofthe via hole at a location that is in alignment with and, thus, oppositefrom its corresponding via hole. A focal point of the laser ispositioned at a location just within the bottom of the via hole. Thus,the laser forms a vent that communicates with the other surface of thesubstrate, as well as a vent hole that establishes communication betweenthe vent and the blind ended via hole.

Since a laser melts or ablates the material of the substrate, residualmaterial may collect on the surfaces of a laser drilled features exposedto the heat of the laser (termed the “heat affected zone”), such as thevent or vent hole. This residual material is referred to as “slag.”Although the laser may form a vent hole with dimensions that are withinreasonable tolerances, the size of the vent hole may be effectivelyreduced, or even closed, by the slag that results from use of a laser toform the vent and vent hole. When slag-obstructed vent holes areundesirably small or occluded, material deposition may not proceed in adesirable fashion. As a consequence, the resulting via may includeundesirable structural defects.

Neither conventional, relatively stagnant etching processes nor ashingeffectively removes the slag.

Accordingly, there are needs for methods and apparatus for flowing orforcing etchants into or through small openings that extendsubstantially through a substrate to remove material from features bywhich the etchant passes.

SUMMARY OF THE INVENTION

The present invention includes processes and apparatus for causing, orforcing, an etchant to flow past a feature, such as a surface, fromwhich material is to be removed. The material may protrude into, belocated along a sidewall of, or obstruct a recess or aperture thatextends into a surface of a substrate.

In one aspect, the present invention includes a method for causing afluid to flow into or through recesses or apertures, also termedopenings, that are formed in or through a substrate. Pressurization ofthe fluid may cause the fluid to flow into or through the recesses orapertures. As an example, the fluid may be pressurized by introducing atleast a portion of a substrate within a volume of fluid and applying adifferential pressure on opposite sides of the substrate. As thedifferential pressure is applied, the fluid flows or is otherwise forcedinto or through recesses or apertures, especially those that extendsubstantially through the substrate. The differential pressure may begenerated across the substrate by applying a positive pressure or anegative pressure to a fixed volume of fluid on one side of thesubstrate. Application of a positive pressure includes applying agreater amount of pressure to one side of the substrate than is presentat the opposite side of the substrate. Application of a negativepressure similarly includes application of a lesser pressure to a sideof the substrate than is present at the opposite side of the substrate.Other nonlimiting examples of the manner in which the fluid may bepressurized include use of a nozzle or other apparatus that directsfluid under pressure toward a surface of a substrate that includesrecesses or apertures, as well as movement of a substrate through avolume of fluid in a direction substantially transverse to a plane ofthe substrate, which movement generates an increased pressure at aleading surface of the substrate.

A differential pressure may be applied in a substantially continuous,substantially constant manner, applied intermittently in a patterned orrandom fashion, oscillated, or even alternated, to reverse the directionin which fluid flows into or through openings that extend substantiallythrough a substrate.

Processes that incorporate teachings of the present invention may beconducted on a single wafer, multiple wafers that are positioned along asingle barrier, or multiple wafers that are oriented parallel to oneanother and arranged in series along a flow path and transverse to thedirection thereof.

The fluid may, by way of example only, comprise an etchant, solvent, orother material that dissolves or is otherwise suitable to removematerial.

A method for altering the internal surfaces of a vent hole, via hole, orother aperture that extends substantially through a substrate includescausing an etchant to flow into or through the apertures. Such processesmay be used to effect a number of ends, including, without limitation,removal of slag from a vent hole at the bottom of a blind ended via, tosmooth the side wall of an aperture that extends substantially throughthe substrate, modification of the configuration of an aperture thatextends substantially through the substrate, or the like.

In another aspect, the present invention includes apparatus and systemsfor pressurizing fluid and causing the same to flow into or throughrecesses or apertures that communicate with a surface of a substrate.Such apparatus and systems include, but are not limited to, differentialpressure apparatus in which a substrate is positioned along a boundarybetween different pressures, apparatus that are configured to pressurizefluid and direct the same toward a surface of a substrate, and apparatusthat are configured to carry a substrate through a volume of fluid suchthat pressure is increased at a leading surface of the substrate.

Other features and advantages of the present invention will becomeapparent to those of ordinary skill in the art through consideration ofthe ensuing description, the accompanying drawings, and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which depict examples of various aspects of the presentinvention:

FIGS. 1 through 3 depict a substrate that may be processed in accordancewith teachings of the present invention to remove obstructions or otherirregularities in, or enlarge, apertures that extend through thesubstrate, with FIG. 1 showing an upper surface of a substrate,

FIG. 2 comprising a partial cross-sectional view through a portion ofthe thickness of the substrate, and

FIG. 3 being a representation of a bottom surface, or back side, of thesubstrate;

FIG. 4 is a schematic representation of a differential pressureapparatus and method for causing etchant or another fluid to flowthrough apertures of a substrate;

FIG. 4A is schematic representation of a variation of the differentialpressure apparatus shown in FIG. 4;

FIGS. 5 and 6 illustrate an example of a differential pressure chamberthat is configured to hold a substrate at a boundary between regions ofdifferent pressure to facilitate flow of fluid through apertures thatextend through or substantially through a substrate;

FIGS. 7 and 8 depict an example of a substrate retainer andcorresponding features on a chamber that that may be included in thedifferential pressure apparatus that incorporates teachings of thepresent invention;

FIGS. 9 and 10 illustrate another example of retainer and correspondingfeatures of a chamber that may be included in a differential pressureapparatus according to the present invention;

FIGS. 11 and 12 represent another example of retainer and correspondingfeatures of a chamber of a differential pressure apparatus of thepresent invention;

FIG. 13 depicts use of a positive pressure to cause etchant to flowthrough an at least partially obstructed aperture of a substrate;

FIG. 14 illustrates use of a negative pressure to cause etchant to flowthrough an at least partially obstructed aperture of a substrate;

FIGS. 15 through 18 are schematic illustrations of apparatus that may beused to simultaneously cause fluid to flow through apertures of aplurality of substrates;

FIG. 19 is a schematic representation of a system for directing fluidunder pressure onto a substrate to cause fluid to flow into or throughrecesses or apertures that communicate with the surface of thesubstrate; and

FIG. 20 schematically depicts a system for moving one or more substratesthrough a volume of fluid to generate an increased pressure at a leadingsurface of the substrate and, thus, cause the fluid to enter into orflow through recesses or apertures that communicate with that surface ofthe substrate.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

With reference to FIGS. 1 through 3, a substrate 110 that includes atleast one aperture 114 extending substantially therethrough isillustrated. Substrate 110 may comprise a full or partial semiconductorsubstrate (e.g., a full or partial wafer of silicon, gallium arsenide,indium phosphide, or another semiconductor material), asilicon-on-insulator (SOI) type substrate (e.g., silicon-on-ceramic(SOC), silicon-on-glass (SOG), silicon-on-sapphire (SOS), etc.), adielectric substrate (e.g., glass, ceramic, an organic material, etc.),or any other material suitable for use in forming electronic componentsthat form or carry one or more conductive circuits.

Apertures 114 may extend partially through a thickness of substrate 110or, as shown, substantially through a thickness of substrate 110 (e.g.,from one major surface 116 thereof to an opposite major surface 122thereof). Without limiting the scope of the present invention, apertures114 may comprise vias that extend through substrate 110. In the case ofblind vias 114 a (with a diameter of, e.g., up to about 50 μm orgreater), which do not extend into one major surface 116 of substrate110, but do not extend completely through substrate 110 (i.e., to theopposite major surface 122), one or more apertures 114 may also includea relatively small vent hole 114 b (with a diameter of, e.g., up toabout 5 μm) that is intended to communicate with blind via 114 a andthat extends into the opposite major surface 122 of substrate 110. Viasor other apertures 114, including, but not limited to, vent holes 114 b,may be formed by a variety of known processes, such as by laser drillingprocesses (e.g., with a laser intermittently pulsed from four or moredifferent angles that converge at a single point). Some processes thatare used to form apertures 114 in or through a substrate may result inobstructions 115 (e.g., material slag from melting or obliteratingsubstrate 110 with a laser, etc.) or other irregularities (e.g., surfaceirregularities, such as roughness, bumps, etc.) within apertures 114.Thus, following the formation of apertures 114, they may not be ready oracceptable for subsequent processing.

FIG. 4 shows a differential pressure apparatus 10, which, withoutlimiting the scope of the present invention, may be used with a fluid,such as an etchant, solvent, or other suitable liquid (e.g., a suitablesurfactant, either separately or in solution with an etchant or solvent,may facilitate wetting of the surfaces of features that are to beremoved by the etchant or solvent) to remove obstructions 115 (FIG. 2)or other irregularities from recesses in (including, without limitation,relatively high aspect ratio recesses) or apertures 114 of a substrate110, or to change a size, shape, or geometry (e.g., between one or moreof cylindrical, hourglass, frustoconical, etc.) of one or more apertures114 (FIGS. 1 through 3) or recesses of substrate 110. Apparatus 10includes a pressurizable chamber 12 for holding a volume of fluid 50,such as an etchant, solvent, or other suitable fluid. A boundary 15,which may be located somewhat centrally within chamber 12, separateschamber 12 into an upstream side 12U and a downstream side 12D,referring to the direction in which an etchant, solvent, or othersuitable fluid moves through chamber 12 when a differential pressure isgenerated across boundary 15. A substrate holder 16 may be positionedwithin chamber 12, along boundary 15.

Chamber 12 includes means for facilitating access to an interior thereofof a type known in the art (e.g., an access panel or door, a lid, etc.),which may seal against a remainder of chamber 12 and, thus, facilitatethe generation of a non-ambient positive or negative pressure withinchamber 12. Without limiting the scope of the present invention, chamber12 may have dimensions or features, such as a heater, cooler, or heattransfer mechanism exposed to fluid 50 or through which fluid 50 iscirculated, that facilitate maintenance of fluid 50 therein at a desiredtemperature.

Substrate holder 16 includes a receptacle 22 for receiving a substrate110. Receptacle 22 includes a sealing element (not shown) that isconfigured to prevent fluid 50 from flowing between substrate holder 16and an outer periphery 112 of substrate 110 as fluid 50 flows throughapertures 114 that extend between opposite major surfaces 116 and 122 ofsubstrate 110 (FIGS. 1 through 3).

FIGS. 5 and 6 show an example of a chamber 12, chamber 412, thatincludes an integral substrate holder 16. Chamber 412 includes two sides412 a and 412 b, each of which defines a volume 421 a, 421 b. Sides 412a and 412 b are configured to be assembled and sealingly securedtogether so that a combined volume 421 defined collectively by sides 412a and 412 b may be pressurized with a positive pressure or a negativepressure. Edges 417 a and 417 b of sides 412 a and 412 b are configuredto abut one another when sides 412 a and 412 b are properly assembledwith each other. A ledge 416 a, 416 b may be recessed just beneath eachedge 417 a, 417 b, and is configured to support peripheral portions 118,124 (FIGS. 1 through 3) of major surfaces 116, 122 of a substrate 110,which is held in positioned at a boundary 415 between volume 421 a and421 b when sides 412 a and 412 b are assembled with each other, withportions of major surfaces 116 and 122 exposed to volumes 421 a and 421b. Together, ledges 416 a and 416 b form a receptacle 22 for a substrate110. One or both of ledges 416 a and 416 b may form a substantiallycontinuous support for peripheral portions 118, 124 of a major surface116, 122 of substrate 110. A sealing element 424 a, 424 b (e.g., anannular gasket, an O-ring, etc.), which may have a somewhat annularshape to facilitate sealing against surface 116, 122 while exposing atleast a portion of surface 116, 122 through a center thereof, may bepositioned on and secured in place (e.g., with adhesive, within a groove430, etc.) relative to each ledge 416 a, 416 b.

A few more, nonlimiting examples of substrate holders 16, theirfeatures, and corresponding features of chambers 12 with which they maybe used are illustrated in FIGS. 7 through 12.

In the example illustrated in FIGS. 7 and 8, substrate holder 16′includes a pair of housing elements 16 a′ and 16 b′ that, whenassembled, are configured to be positioned on opposite sides ofsubstrate 110 (i.e., adjacent to surfaces 116 and 122). Interiorsurfaces 17 a′ and 17 b′ of housing elements 16 a′ and 16 b′,respectively, are configured to face one another when housing elements16 a′ and 16 b′ are assembled. Each housing element 16 a′, 16 b′includes an opening 26 a′, 26 b′, which appears as a window, havingsubstantially the same shape as and slightly smaller dimensions (e.g.,diameter) than substrate 110. Interior surface 17 a′, 17 b′ of one orboth housing elements 16 a′, 16 b′ may include a recess 28 a′, 28 b′that is located around, or circumscribes, an entire periphery of opening26 a′, 26 b′. Recess 28 a′, 28 b′ is configured to at least partiallyreceive a peripheral portion 118, 124 of a major surface 116, 122 ofsubstrate 110, and may position substrate 110 at a desired locationrelative to opening 26 a′, 26 b′. Thus, housing elements 16 a′ and 16 b′and recess 28 a′, 28 b′, if any, form a receptacle for substrate 110.

With continued reference to FIG. 7, sealing element 24 a′, 24 b′ isassociated with recess 28 a′, 28 b′ to seal against substrate 110, at ornear outer periphery 112 thereof. As shown, sealing element 24 a′, 24 b′may comprise a ring of compliant material (e.g., silicone or anotherelastomer), which may be seated within a groove (not shown) formed inrecess 28 a′, 28 b′ or otherwise secured in place relative to recess 28a′, 28 b′. Sealing element 24 a′, 24 b′ may be sized and configured forplacement against a major surface 116, 122 of substrate 110, near outerperiphery 112 thereof (i.e., against peripheral portion 118, 124), asshown, or for placement against outer periphery 112 or a corner 120, 126formed at the junction between a major surface 116, 122 and outerperiphery 112.

As shown in FIG. 8, without limiting the scope of the present invention,an assembled, secured substrate holder 16′ includes an outer edge 32′,which may be received within a groove 34′ formed in chamber 12′ todefine a boundary within chamber 12′. Groove 34′ may extend completelyaround an interior surface of chamber 12′. A sealing element 38′ may belocated within groove 34′ (e.g., within a subgroove (not shown), withina base 36′ of groove 34′, etc.) and configured to seal against outeredge 32′ of substrate holder 16′.

With reference to FIGS. 9 and 10, another example of substrate holder16″ and the chamber 12″ within which it is located are depicted.Substrate holder 16″, which is fixed within or comprises an integralpart of chamber 12″, defines a sealable boundary 15″ between an upstreamside 12U″ and a downstream side 12D″ of chamber 12″.

Substrate holder 16″ includes a fixed element 16 a″, which extends alongboundary 15″ inwardly from portions of an interior surface of chamber12″ that define the entire outer periphery of boundary 15″. An opening26 a″, which has dimensions that facilitate exposure of a substantialportion (e.g., substantially all, device or interposer bearing regions,etc.) of substrate 110 without exposing outer periphery 112 of substrate110 is located centrally or somewhat centrally through fixed element 16a″. A recess 28 a″ may circumscribe an entire periphery 27 a″ of opening26 a″ within a substrate-carrying surface 17 a″ of fixed element 16 a″.Recess 28 a″ may be configured to at least partially receive aperipheral portion 118, 124 (FIGS. 1 through 3) of a major surface 116,122 of substrate 110 and, optionally, to position substrate 110 at adesired location relative to opening 26 a″. Without limiting the scopeof the present invention, substrate-carrying surface 17 a″ of fixedelement 16 a″ may face upstream side 12U″ of chamber 12″. In thisembodiment, substrate-carrying surface 17 a″ and recess 28 a″, if any,serve as a receptacle for substrate 110.

A sealing element 24 a″, which is configured to abut and seal againstsubstrate 110 may be carried by and, optionally, secured tosubstrate-carrying surface 17 a″ of fixed element 16 a″, aroundperiphery 27 a″ of the opening 26 a″ therethrough. By way of nonlimitingexample, sealing element 24 a″ may be held within a groove (not shown)that circumscribes periphery 27 a″ of opening 26 a″ or otherwise besecured to substrate-carrying surface 17 a″. If substrate carryingsurface 17 a″ of fixed element 16 a″ faces upstream side 12U″ of chamber12″, when a substrate 110 is assembled with fixed element 16 a″, againstsealing element 24 a″, a pressure differential may be established acrosssubstrate 110 and substrate holder 16″. The presence of a greaterpressure within upstream side 12U″ than in downstream side 12D″ ofchamber 12″ will hold substrate 110 in place against fixed element 16a″, over opening 26 a″, and against sealing element 24 a″, therebymaintaining and facilitating an increase in pressure differentialbetween upstream side 12U″ and downstream side 12D″, if necessary ordesired.

Optionally, substrate holder 16″ may include a retainer 16 b″positionable over a substrate 110 that has been assembled with fixedelement 16 a″. Retainer 16 b″ has smaller dimensions than fixed element16 a″ to facilitate positioning of retainer 16 b″ over, as well as itsremoval from, fixed element 16 a″. Retainer 16 b″ includes an opening 26b″ that is configured to substantially align with opening 26 a″ of fixedelement 16″ and to expose a substantial portion of a major surface 116,122 of substrate 110. Additionally, retainer 16 b″ may include a recess28 b″ on a substrate-facing surface 17 b″ thereof, which surface is alsoconfigured to face substrate-carrying surface 17 a″ of fixed element 16a″ as retainer 16 b″ is positioned over, assembled with, and secured tofixed element 16 a″. Like recess 28 a″, recess 28 b″ may be configuredto receive a peripheral portion 118, 124 (FIGS. 1 and 3) of a majorsurface 116, 122 of substrate 110 and, optionally, to position substrate110 at a desired location relative to opening 26 b″. A sealing element,cushion, or other gasket (not shown) may be associated withsubstrate-facing surface 17 b″ of retainer 16 b″ to establish a sealagainst or protect a major surface 116, 122 of substrate 110 as retainer16 b″ is positioned over substrate 110.

Retainer 16 b″ may be secured to fixed element 16 a″ by any suitablemeans for engagement 60″ within the abilities of one of skill in the art(e.g., one or more clamping elements on fixed element 16 a″ that engageedges of retainer 16 b″; features that facilitate rotatable engagementbetween fixed element 16 a″ and retainer 16 b″, such as correspondingtabs and slots or complementary threads, etc.).

Turning now to FIGS. 11 and 12, another example of substrate holder 16′″and a portion of the chamber within which it resides are depicted.

Opposed, parallel sides 16 a′″ and 16 b′″ of a base 16B′″ of substrateholder 16′″ are arranged so as to define a narrow slot 25W″, orreceptacle, within which a substrate 110 may be disposed. A ledge 28B′extending between sides 16 a′″ and 16 b′ of base 16B′″ is configured tosupport substrate 110 and to align the same between opposed openings 26a′″ and 26 b′″ of sides 16 a′″ and 16 b′″, respectively. A sealingelement 24B′″ may be positioned on and, optionally, secured to ledge28B′″ so as to form a seal against an outer periphery of substrate 110that has been inserted into slot 25B′″ as sufficient pressure is appliedto substrate 110 (e.g., by a snug fit between outer periphery 112 (FIGS.1 and 3) of substrate 110 and sealing element 24B′″, by placing a loadon substrate 110 along a vector that creates a seal between outerperiphery 112 thereof and sealing element 24B″, or by a combination ofthe foregoing).

Of course, base 16B′″ of substrate holder 16′″ may be configured suchthat, when a substrate 110 that has been inserted into slot 25B″, aportion of substrate 110 protrudes from or is otherwise exposed beyondbase 16B′″ (e.g., a major surface 116, 122 thereof through opening 26b′″, a portion of outer periphery 112 thereof, etc.) to facilitateremoval of substrate 110 from slot 25B′″ (e.g., with edge-engagingapparatus, as known in the art; with surface-engaging apparatus, asknown in the art; manually, etc.).

In addition to base 16B′″, substrate holder 16′″ may include anengagement element 16E′″, which may be fixed to an inner surface of achamber (not shown) or may be separate from the inner surface andconfigured to sealingly engage the same. Engagement element 16E′″ isconfigured to be assembled with and to releasably engage base 16B′″ ofsubstrate holder 16′″. For example, an engagement element 16E′″ that isintegral with or fixed relative to the inner surface of the chamber maybe assembled with base 16B′″ when the chamber is closed and sealed. Inthe example of an engagement element 16E′″ that is separate from theinner surface of the chamber, assembly may occur before the chamber withwhich substrate holder 16′″ is configured to be used is closed andsealed. Thereafter, the inner surface of the chamber may seal againstengagement element 16E′″ as the chamber is closed and sealed.

As illustrated, engagement element 16E′″ includes opposed, parallelsides 16 c′″ and 16 d′″, which define a narrow slot 25E′″ therebetween.Sides 16 c′ and 16 d′″ and slot 25E′″ of engagement element 16E′″ arerespectively configured to align with sides 16 a′″ and 16 b′″ and slot25B′″ of base 16B′″ when base 16B′″ is assembled with engagement element16E′″. In this manner, slot 25E′″ may receive a substrate 110 that hasbeen positioned within slot 25B′ of base 16B′″ as engagement element16E′″ is aligned, if necessary, and assembled with base 16B′″. Thus,when base 16B′″ and engagement element 16E′″ are assembled, slots 25B′″and 25E′″ together form a receptacle 22″ for substrate 110.

Like base 16B′″, engagement element 16E′″ also includes a ledge 28E′″between sides 16 c′″ and 16 d′″. Ledge 28E′″ carries a sealing element24E′″ that is configured to abut a portion of outer periphery 112 ofsubstrate 110 that is not engaged by sealing element 24B′″ of base 16B′″when engagement element 16E′″ is assembled with a substrate 110-carryingbase 16B′″.

Without limiting the scope of the present invention, base 16B′″ andengagement element 16E′″ of substrate holder 16′″ may be mechanicallyassociated with one another in any suitable manner that is within theskill of one in the art (e.g., with a simple hinge that establishes aclam-shell type relationship between base 16B′″ and engagement element16E′″, a more complex mechanism that automatically aligns engagementelement 16E′ over base 16B′″ as these elements are assembled and,optionally, maintains the assembled relationship between these elements,etc.).

Engagement element 16E′″ may optionally include at least one engagementfeature 60E′″ which is configured to engage a corresponding engagementfeature 60B′″ of base 16B′″ and, thus, to maintain the assembledrelationship between base 16B′″ and engagement/release element 16E′″ ofsubstrate holder 16′″.

With an understanding of the broad concepts of the various aspects ofthe present invention, various embodiments of differential pressureapparatus, chambers 12 and substrate holders 16 will be apparent tothose of ordinary skill in the art.

With returned reference to FIG. 4, additional features of a differentialpressure apparatus 10 according to the present invention are described.An optional inlet 18 may communicate with upstream side 12U of chamber12 to allow fluid 50 to flow therein or therefrom, while an optionaloutlet 20 may communicate with downstream side 12D of chamber 12 toallow fluid 50 to flow therein or therefrom. As illustrated, inlet 18and outlet 20 may be coupled to a pump 40, which generates adifferential pressure across boundary 15 of chamber 12 and, thus, acrosssubstrate 110 by simultaneously drawing fluid 50 from one side 12U, 12Dof chamber 12 and pumping fluid 50 into the other side 12D, 12U ofchamber 12.

Optionally, although not shown, inlet 18 and/or outlet 20 maycommunicate with one or more reservoirs or fluid sources to facilitatethe introduction of different types of fluids within at least a portionof chamber 12 at a particular point during processing of a substrate110. As an example, it may be desirable to expose a substrate 110 to asurfactant-containing solution prior to exposing substrate 110 to anetchant or solvent. Likewise, it may be desirable to rinse substrate 110and apertures 114 thereof following processing thereof with a particulartype of fluid 50.

Alternatively, as shown in FIG. 4A, in addition to, or in combinationwith inlet 18 and outlet 20, a pressurization component may beassociated with (e.g., communicate with) one or both of upstream side12U and downstream side 12D of chamber 12. For example, and withoutlimiting the scope of the present invention, a source 42 of positivepressure may be associated with upstream side 12U or a source 44 ofnegative pressure may be associated with downstream side 12D.Alternatively, either source 42 or 44 may be configured to selectivelyincrease or decrease pressure within a corresponding side 12U, 12D ofchamber 12. Either source 42, 44 may be configured to change thepressure in the side 12U, 12D of chamber 12 with which it is associatedby changing the amount of fluid within that side 12U, 12D of chamber 12.For example, source 42 may create a relatively higher pressure withinupstream side 12U by introducing a fluid, such as fluid 50, or anotherfluid (e.g., gas, liquid, etc.) that is inert or compatible with fluid50 without displacing a significant portion of fluid 50 from upstreamside 12U. Conversely, source 44 may create a relatively lower pressurewithin downstream side 12D of chamber 12 by removing fluid 50 or gasfrom downstream side 12D. Various types of pumps and associated motorsmay be used as source 42 or source 44, as known in the art.

Other features of differential pressure apparatus 10, including meansfor controlling a temperature of fluid 50 (as an other-than-ambienttemperature may be required or desirable for the desired processing;e.g., silicon etchants are more effective at elevated temperatures,etc.), means for introducing substrate holder 16 into chamber 12, meansfor operating substrate holder 16, means for handling substrates 110,means for closing and sealing chamber 12, means for introducing fluid 50into chamber 12 and removing fluid 50 from chamber 12, and the like,will be apparent to and understood by one of skill in the art.

Directing reference again to FIG. 4, when a substrate 110 has beenplaced within substrate holder 16, substrate holder 16 or a portionthereof has been sealed against an inner surface of chamber 12, ifnecessary, and chamber 12 is sealed, substrate holder 16 and substrate110 together form a physical boundary, which is positioned alongboundary 15, that facilitates the generation of a differential pressurewithin chamber 12 (i.e., a different amount of pressure within upstreamside 12U from that within downstream side 12D).

Once substrate 110 has been placed within receptacle 22 of substrateholder 16 and the assembly of substrate holder 16 and substrate 110effectively isolates upstream side 12U of chamber 12 from downstreamside 12D of chamber 12, a pressure differential may be applied acrossborder 15 and, thus, across substrate 110. FIGS. 13 and 14 provide twoexamples of the manner in which a pressure differential may be applied,or generated, across substrate 110.

Referring first to FIG. 13, a pressure differential may be generated byapplying a positive pressure to upstream side 12U of chamber 12. Theamount of positive pressure applied exceeds an ambient pressure withindownstream side 12D of chamber 12. Positive pressure may be applied, bya pump 40 or other pressure source (e.g., source 42 shown in FIG. 4A)that communicates with upstream side 12U of chamber, by introducing afluid (e.g., gas, liquid, such as additional fluid, etc.) into thesealed upstream side 12U of chamber 12 without displacing any of thefluid previously present within upstream side 12U. The presence ofgreater pressure on upstream side 12U than downstream side 12D causesfluid 50 from upstream side 12U to enter into recesses or apertures 114(FIGS. 1 through 3) of substrate 110, which is located at the boundary15 between a relatively higher pressure and a relatively lower pressure,and to flow into downstream side 12D. As fluid 50 flows into and throughapertures 114, desired processing may be effected, such as removal ofany obstructions 115 (FIG. 2) or other irregularities (e.g., bumps,protrusions, surface roughness, etc.) within apertures 114 by a fluid 50that includes one or more etchants, solvents, or other suitable fluids.The flow of fluid 50 past obstructions 115 or any other irregularitiesmay expedite the removal process.

Turning now to FIG. 14, instead of, or in addition to, increasingpressure within upstream side 12U of chamber 12, pressure withindownstream side 12D of chamber 12 may be decreased. For example, as pump40 operates (or as source 44 of negative pressure, shown in FIG. 4A(e.g., a vacuum, another pump for removing fluid from downstream side12D, etc.)) operates, fluid (e.g., gas, such as air, liquid, such asfluid 50, etc.) may be removed from a downstream side 12D of chamber 12without substantially replacing or displacing (with the exception of thefluid that flows through apertures 114) (FIGS. 1 through 3) the fluidthat has been removed from downstream side 12D. The lesser pressure ondownstream side 12D than upstream side 12U causes fluid 50 to be drawnfrom upstream side 12U, into apertures 114 of substrate 110, which islocated at the boundary 15 between a relatively high pressure and arelatively low pressure, and into downstream side 12D. As fluid 50 flowsinto and through apertures 114, desired processing may be effected.

A differential pressure may be applied in a substantially continuous,substantially constant manner, applied intermittently in a patterned orrandom fashion, oscillated, or even alternated, to reverse the directionin which etchant flows into or through recess or apertures 114 thatextend substantially through a substrate 110 (see FIGS. 1 through 3).

As the difference in pressure across a boundary 15, or the amount of thepressure differential, may correspond to the rate at which fluid 50flows through apertures 114 (FIGS. 1 through 3) and, thus, the amount offluid 50 that flows past an obstruction 115 or other irregularity over agiven period of time, the difference in pressure may also correspond tothe rate at which material is removed from apertures 114 or surfacesthereof.

In addition to differential pressure apparatus that are configured tohold and process a single substrate 110 at a time, differential pressureapparatus configured to hold and process two or more substrates 110simultaneously are also within the scope of the present invention, asshown in FIGS. 15 through 17.

For example, FIG. 15 depicts a differential pressure apparatus 210 thatincludes a chamber 212 with a frame 213 that is positioned along aboundary 215 that surrounds a centrally or somewhat centrally locatedportion 212 a of chamber 212 and separates the same from a peripherallylocated portion 212 b of chamber 212. Frame 213 is configured to carry aplurality of substrate holders 16. When substrates 110 are assembledwith substrate holders 16, substrate holders 16 are assembled with frame213, if necessary, and chamber 212 is sealed, frame 213, substrateholders 16, and substrates 110 collectively isolate portion 212 a fromportion 212 b in such a way that a differential pressure may begenerated across boundary 215. As this configuration of differentialpressure apparatus 210 positions substrates 110 along a single boundary,it may be said that differential pressure apparatus 210 positionssubstrates 110 “in parallel” to one other, whether or not substrates 110are actually oriented parallel to each other.

FIG. 16 illustrates a differential pressure apparatus 210′ that includesa pressurizable chamber 212′ with two spaced apart boundaries 215 a′ and215 b′ therein. Boundaries 215 a′ and 215 b′ define a central region 212a′ between two outer regions 212 b′. A substrate holder 16 that carriesa substrate 110 may be positioned substantially along each boundary 215a′, 215 b′ to facilitate the generation of a differential pressure, inparallel, across each boundary 215 a′, 215 b′. One or morepressurization components 240′ may be associated with chamber 212′ insuch a way as to vary a pressure in central region 212 a′ relative tothe pressure with each outer region 212 b′. If, for example, arelatively lower pressure is generated within central region 212 a′,fluid 50 may be drawn from outer regions 212 b′, through apertures 114(FIGS. 1 through 3) in substrates 110, and into central region 212 b′.Alternatively, if a relatively higher pressure is generated withincentral region 212 a′ than the pressure present within outer regions 212b′, fluid 50 may be forced from central region 212 a′, through apertures114, and into outer regions 212 b′.

In FIG. 17, another example of differential pressure apparatus 210″ isshown. Differential pressure apparatus 210″ is configured similarly todifferential pressure apparatus 10, but includes a frame 213″, whichcarries two or more substrate holders 16, positionable substantiallyalong a boundary 215″ of a pressurizable chamber 212″ to separate andupstream side 212U″ of chamber 212″ from a downstream side 212D″thereof.

Referring to FIG. 18, another example of a differential pressureapparatus 210′″ that is configured to hold and process two or moresubstrates 110 is depicted. Differential pressure apparatus 210′″includes plural substrate holders 16 that are oriented “in series.” As asubstrate 110 is assembled with each substrate holder 16, chamber 212′″is sealed, and different regions 212 a′″, 212 b′″, 212 c′″, etc., aresubstantially isolated from one another, a pressure differential may begenerated from a region 212 a′″ at a first end of chamber 212′″ and aregion 212 c′″ at an opposite end of chamber 212′″. As in the previouslydescribed embodiments of differential pressure apparatus, the pressuredifferential causes fluid 50 to be forced or drawn into or throughapertures 114 (FIGS. 1 through 3) in substrates 110.

Of course, differential pressure apparatus that are configured toposition at least one substrate 110 in parallel with at least one othersubstrate 110 and in series with still another substrate 110 are alsowithin the scope of the present invention.

In addition to the generation of a pressure differential across aboundary, other means and techniques for pressurizing fluid 50 (see,e.g., FIG. 4) are also within the scope of the present invention. Forexample, as shown in FIG. 19, fluid 50 under pressure (e.g., by anappropriate nozzle 350, etc.), may be directed toward a surface 116, 122of substrate 110 and into apertures 114 (FIGS. 1 through 3) or recessesthat communicate with surface 116, 122. As another example, as FIG. 20schematically depicts, a substrate holder 316 may carry one or moresubstrates 110 through a volume 312 of fluid 50, generating an increasein pressure across a leading surface 116, 122 (FIGS. 1 through 3) ofsubstrate 110 and forcing fluid 50 into apertures 114 or recesses thatcommunicate with leading surface 116, 122. Of course, from thedescription provided hereby, a variety of other apparatus and techniquesfor pressurizing fluid 50 and forcing the same to flow into or throughapertures 114 or recesses in a substrate 110 may be readily apparent toone of skill in the art and, thus, are also within the scope of thepresent invention.

Moreover, teachings of the present invention are not limited to use withfluids 50 that are configured to remove obstructions 115 or otherirregularities from apertures 114 or recesses in a substrate 110.Without limiting the scope of the present invention, teachings thereofmay also be used to cause fluids that react with material at thesurfaces of apertures 114 or recesses or that deposit or coat materialsonto the surfaces of apertures 114 or recesses to flow into or throughapertures 114 or recesses of a substrate 110.

Although the foregoing description contains many specifics, these shouldnot be construed as limiting the scope of the present invention, butmerely as providing illustrations of some of the presently preferredembodiments. Similarly, other embodiments of the invention may bedevised which do not depart from the spirit or scope of the presentinvention. Features from different embodiments may be employed incombination. The scope of the invention is, therefore, indicated andlimited only by the appended claims and their legal equivalents, ratherthan by the foregoing description. All additions, deletions andmodifications to the invention as disclosed herein which fall within themeaning and scope of the claims are to be embraced thereby.

1. A method for removing material from surfaces of at least one recessor at least one aperture extending into a surface of a substrate,comprising pressurizing fluid so as to cause the fluid to flow into theat least one recess or at least one aperture.
 2. The method of claim 1,wherein pressurizing fluid comprises generating a pressure differentialacross a boundary along which the substrate is substantially positioned.3. The method of claim 1, wherein pressurizing fluid comprises directingfluid under pressure toward the surface of the substrate.
 4. The methodof claim 1, wherein pressurizing fluid comprises moving the substrate,with the surface thereof facing forward, through a volume of fluid. 5.An apparatus for generating a pressure differential across a substrate,comprising: a chamber; at least one substrate holder locatedsubstantially along at least one boundary within the chamber andconfigured to hold a substrate such that fluid communication between afirst region of the chamber and a second region of the chamber islimited to at least one aperture extending substantially through thesubstrate; and at least one pressurization component associated with atleast one of the first region of the chamber and the second region ofthe chamber.
 6. The apparatus of claim 5, wherein the at least onesubstrate holder comprises a plurality of substrate holders in parallelalong the at least one boundary.
 7. The apparatus of claim 6, furthercomprising a frame configured to carry the plurality of substrateholders.
 8. The apparatus of claim 5, wherein the at least one substrateholder comprises a plurality of substrate holders in series along the atleast one boundary.
 9. The apparatus of claim 5, wherein the firstregion of the chamber is located between a first substrate holder and asecond substrate holder.
 10. The apparatus of claim 5, wherein the atleast one substrate holder comprises at least one sealing elementconfigured to seal against at least one of a peripheral edge and aperipheral portion of a surface of the substrate.
 11. The apparatus ofclaim 5, wherein at least a portion of the at least one substrate holderis fixed to at least one inner surface of the chamber.
 12. The apparatusof claim 5, wherein at least a portion of the at least one substrateholder is configured to seal against at least one inner surface of thechamber.
 13. The apparatus of claim 5, wherein the at least onesubstrate holder comprises at least two assemblable elements forretaining the substrate.
 14. The apparatus of claim 5, wherein the atleast one substrate holder is configured to maintain a position of thesubstrate over an opening of the substrate holder.
 15. The apparatus ofclaim 5, wherein a pressure in the first region of the chamber isgreater than a pressure in the second region of the chamber.
 16. Theapparatus of claim 15, wherein the at least one pressurization componentcomprises a source of positive pressure associated with the first regionof the chamber.
 17. The apparatus of claim 15, wherein the at least onepressurization component comprises a source of negative pressureassociated with the second region of the chamber.
 18. The apparatus ofclaim 5, wherein the at least one pressurization component is configuredto selectively modify pressure within at least one of the first regionof the chamber and the second region of the chamber.
 19. A differentialpressure apparatus, comprising: a chamber; at least one substrate holderlocated substantially along at least one boundary within the chamber andcomprising: at least one recess configured to support a peripheralportion of a substrate; at least one opening configured to expose asubstantial portion of the substrate proximate the peripheral portion ofthe substrate; and at least one sealing element configured to limitfluid communication between a first region of the chamber and a secondregion of the chamber to at least one aperture extending substantiallythrough the substrate; and at least one pressurization component. 20.The apparatus of claim 19, wherein the at least one pressurizationcomponent is associated with at least one of the first region of thechamber and the second region of the chamber.
 21. The apparatus of claim19, wherein the substrate holder is configured to carry the substratethrough a volume of fluid.
 22. The apparatus of claim 19, wherein the atleast one pressurization component is configured to pressurize at leastone of an etchant, a solvent, and a surfactant.
 23. The apparatus ofclaim 22, wherein the pressurization component is further configured todirect the at least one of an etchant, a solvent, and a surfactanttoward the substrate.
 24. A method for removing obstructions orirregularities from surfaces of at least one aperture that extendssubstantially through a substrate, comprising forcing an etchant into anopening of the at least one aperture at a first surface of thesubstrate, through the at least one aperture, and out an opening of theat least one aperture at a second surface of the substrate.
 25. Themethod of claim 24, wherein forcing comprises forcing the etchant intoand through the at least one aperture in a pulsed manner.
 26. The methodof claim 24, further comprising forcing the etchant into the opening ofthe at least one aperture at the second surface of the substrate,through the at least one aperture, and out of the opening at the firstsurface of the substrate.
 27. The method of claim 26, wherein forcingthe etchant into the opening of the at least one aperture at the firstsurface of the substrate and forcing the etchant into the opening of theat least one aperture at the second surface of the substrate areeffected sequentially.